PORTLAND – Police from a number of southern Maine communities are comparing notes as they investigate a spate of armed robberies during the past two months at banks, pharmacies and other businesses in the region.

Since November, at least 15 robberies were reported in Cumberland, York and Androscoggin counties. Nearby areas of New Hampshire had at least two bank holdups during that period.

More than two dozen investigators and supervisors met Tuesday in Portland to map out a strategy for thwarting robberies and apprehending those involved.

One purpose of the meeting was to explore how many of the robberies may be connected. Police cited similarities in some of the holdups but said there were significant differences in others.

“I can’t remember such a brief period where there have been so many holdups,” said Cumberland County Sheriff Mark Dion, whose detectives are investigating a robbery Saturday at a Standish branch of Gorham Savings Bank.

The robber fired a shot inside the bank, but no one was injured. In other cases, robbers have pointed guns in their victims’ faces, police said.

Drugs were evidently the motive in pharmacy robberies, such as those in Waldoboro and Bridgton, said State Police Lt. Brian McDonough, head of the criminal investigations division for southern Maine.